JPH0777700A - Information recording / reproducing method and apparatus having dynamic range expanding function - Google Patents

Abstract

(57) [Summary] [Purpose] To widen the recordable dynamic range. [Structure] An optical sensor in which a photoconductive layer is formed on an electrode and an information recording medium in which a polymer dispersed liquid crystal layer in which liquid crystal is dispersed and fixed in a resin are formed on an electrode are arranged to face each other with a gap, and exposure optical In a method of recording an image by applying a voltage simultaneously with image exposure through a system, a recording area is divided into a plurality of areas, and a plurality of images having different tones are simultaneously recorded by different recording conditions for each area, It is characterized in that a plurality of images having different tones are combined after reading.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a liquid crystal dispersed in a resin,
The present invention relates to an information recording / reproducing method and apparatus having a dynamic range expanding function using a fixed polymer dispersed liquid crystal recording medium.

[0002]

2. Description of the Related Art FIG. 1 shows the structure of an image recording apparatus using a polymer dispersed liquid crystal medium. In the figure, 10 is an optical sensor and 20 is a liquid crystal recording medium. The optical sensor 10 includes a transparent support 12, a transparent electrode 12, and a photoconductive layer 1.
In the liquid crystal recording medium 20, the electrode 22 and the polymer dispersion type liquid crystal layer 23 are sequentially laminated on the support 21. As the photoconductive layer, amorphous selenium, amorphous silicon or the like as the inorganic conductive layer, a single layer of polyvinylcarbazole to which trinitrofluorenone is added as the organic photoconductive layer, or an azo-based pigment such as polyvinyl butyral as the charge generation layer It is possible to use, for example, a layer in which the hydrazone derivative is mixed with a resin such as polycarbonate as a charge transfer layer and which is laminated as a charge transfer layer. As the electrode 22 of the liquid crystal recording medium, a transparent electrode such as ITO or an opaque electrode such as A1 electrode can be used.

Such an optical sensor 10 and a liquid crystal recording medium 2
When 0s are arranged facing each other and a voltage is applied between the electrodes 12 and 22 by a power source 30 and visible light is irradiated as writing light as shown in the drawing, the conductivity of the photoconductive layer 13 changes according to the exposure intensity. Then, the voltage applied to the liquid crystal layer 23 changes, the alignment state of the liquid crystal layer changes, and the state is maintained even after the applied voltage is turned off to remove the electric field, and the image information is recorded.

The recording information thus recorded can be converted into an electric signal by a reading device as shown in FIG. That is, as for the light from the light source 40, only the light having an appropriate wavelength is irradiated onto the liquid crystal recording medium 20 through the filter 50. Since the liquid crystal recording medium has a different transmittance depending on the recorded information, it is modulated here, and the modulated light Is received by a photoelectric conversion device 60 such as a CDD line sensor and converted into an electric signal. This electric signal can be output by a CRT or a printer as needed.

[0005]

When an image is recorded by such a method, for example, when a person or the like is photographed in natural light, the dynamic range is narrow. There is a problem that the dark part is crushed when trying to express the highlight part.

An object of the present invention is to solve the above problems, and an object thereof is to provide an information recording / reproducing method and apparatus having a dynamic range expanding function capable of widening a recordable dynamic range for recording.

[0007]

The present invention has been made in view of the above problems, and relates to an image recording / reproducing method and apparatus for expressing a wide exposure range from a dark portion to a highlight. The dynam range expanding method of the present invention will be described in detail below with reference to the drawings. FIG. 3 shows the time variation of the voltage applied to the liquid crystal recording medium in the present invention. As shown in FIG. 1, the optical sensor and the liquid crystal recording medium are arranged so as to face each other and a voltage is applied between both electrodes to expose the exposed portion. It is a plot of voltage changes applied to the liquid crystal recording medium in the (light part) and the unexposed part (dark part). Since both the optical sensor and the liquid crystal recording medium are represented by a parallel circuit of resistance and capacitance in the equivalent circuit, they increase exponentially with their respective time constants.
Note that V _TH is a voltage at which the liquid crystal recording medium starts modulation.

In the recording system of the present invention, when an image is recorded on the liquid crystal recording medium, the voltage is normally turned off when the voltage applied to the liquid crystal recording medium in the dark portion becomes V _TH or more, but the voltage is turned off. The recorded characteristics are different at time, for example, time t1 and t2 in FIG. Figure 4
(A) shows the relationship between the exposure amount and the read signal (modulation degree) when the gray scale is projected and exposed on the recording medium of the present invention when the voltage application time is t1 and t2,
The characteristic A has a voltage application time t1, and the characteristic B has a voltage application time t2. The degree of modulation is such that the liquid crystal recording medium is irradiated with reading light, the transmitted light at that time is read by the CCD sensor, and the signal is A / D converted. The minimum transmittance is zero, the maximum transmittance is 255, and 0 to 255. It is shown in the value of. Characteristic A
As can be seen from the figure, when the voltage is turned off at time t1, the voltage applied to the liquid crystal medium in the dark portion is immediately after V _TH , so the liquid crystal recording medium in the dark portion is hardly modulated, and the transmittance is almost zero. is there. On the other hand, as can be seen from the characteristic B, when the voltage is turned off at the time t2, it takes some time after the voltage in the dark portion reaches V _TH , so that the liquid crystal recording medium in the dark portion is considerably modulated (transmittance T0). . Comparing these two recording methods, the voltage is OF
In the case of F, recording can be performed without saturation even with a large exposure amount as compared with the case of turning off the voltage at time t2, but in the low exposure amount region, the change rate of the modulation degree is low and noise is relatively large. Therefore, when the voltage is turned off at time t1, the minimum amount of exposure that can be recorded is larger than when the voltage is turned off at time t2. From this, the voltage is turned to O at time t1.
The exposure range that can be recorded regardless of whether FF is performed or the voltage is turned off at time t2 (ΔE ₁ in FIG. 4,
The magnitude of ΔE ₂ ) does not change much. However, since the exposure ranges that can be recorded are different between the two, the dynam range can be expanded to ΔE ₃ by dividing the input light into two, recording simultaneously with each method, and then combining the two images. The following method is possible as a method of recording images with different exposure ranges by changing the degree of modulation of the dark portion of the liquid crystal recording medium.

As shown in FIG. 5, two types of photosensors 1 and 2 having different conductivity in the dark part are used as photosensors to be combined with the liquid crystal recording medium. The two types of photosensors are irradiated, and at the same time, the same voltage is applied for the same time using a common power source. FIG. 7 shows the result of simulating the voltage applied to the liquid crystal medium at this time. Assuming that the liquid crystal recording medium is a medium A combined with an optical sensor having a large dark current and the liquid crystal recording medium is a medium B combined with a small dark current, the voltage of the medium A (characteristic M1 in FIG. 7) is the medium B (characteristic M in FIG. 7).
It is higher than in 2) and reaches the threshold sooner. When the applied voltage is turned off when the voltage of the medium B reaches the threshold value of the liquid crystal recording medium, the medium A is considerably modulated, so that images of different exposure ranges can be recorded as shown in FIG. .

Further, as shown in FIG. 6, two kinds of liquid crystal media 1 and 2 having different resistance values are used for the same optical sensor, or liquid crystal recording media having different threshold values are combined,
By exposing the image in the same manner as in the case of FIG. 5 and applying a voltage, images of two types of exposure ranges can be recorded. When liquid crystal recording media having different resistance values are used, when the same voltage is applied, the medium having a large resistance will sooner reach the threshold value of the liquid crystal recording medium, and the modulation will be faster. The larger resistance value has the characteristic M1 in FIG. 7, and the smaller resistance value has the characteristic M2 in FIG. Further, as shown in FIG. 9, images having different exposure ranges can be recorded by changing the voltage application time even if the characteristics of the liquid crystal recording medium are the same, and as shown in FIG. When (threshold value 1 and threshold value 2) are used, if the other physical properties such as resistance are the same, the lower threshold value causes faster modulation, and the combination of these methods will cause a difference. Images in the exposure range can be recorded.

As a method of producing a liquid crystal recording medium having different resistance, there is a method of decreasing the resistance value by changing the amount of ultraviolet irradiation or adding an additive such as an ionic substance in the process of producing the liquid crystal recording medium. Conceivable. Further, as a method of changing the threshold value of the liquid crystal medium, there are a method of changing a liquid crystal substance, a method of changing a ratio of a nematic liquid crystal which uses a small amount in addition to the smectic liquid crystal as a main component, and the like.

Further, the same liquid crystal recording medium and optical sensor are used, and the electrodes are patterned as shown in FIG. 11 to divide into two partial electrodes 1 and 2, and the image exposure is carried out by the above-mentioned method. At the same time, different voltages or voltage application times are applied by the two power sources 1 and 2, and images of two types of exposure ranges can be produced. FIG. 8 shows the calculation result of the voltage applied to the liquid crystal medium when the applied voltage is changed. The higher the applied voltage, the faster the threshold value of the liquid crystal recording medium and the faster the modulation.

All of the above methods utilize the fact that the exposure range of a recordable image can be changed by changing the degree of modulation of the dark portion of the liquid crystal recording medium. As a method of changing the modulation degree of the dark portion of the liquid crystal recording medium, not only the above-mentioned methods but also a method of combining these methods, a method of changing the film thickness of the optical sensor layer, the liquid crystal recording layer, or the like can be considered.

Further, two images with different exposure ranges are produced by using two types of optical sensors having different photoelectric flow rates generated for the same light intensity, and the exposure range is obtained by synthesizing these two types of images. It may be enlarged. As a method for producing an optical sensor having a different photocurrent, a method of changing the pigment used in the charge generation layer or the charge transfer agent in the charge transfer layer, or changing the mixing ratio of the charge transfer agent and the binder resin can be considered. Further, if the characteristics of the optical sensor are changed by these methods, the conductivity of the dark portion is likely to change at the same time, and thus a method combined with the method described above may be used.

Further, it is possible to record images of different exposure ranges by dividing the light into two lights having different exposure intensities and performing image exposure without changing the liquid crystal recording medium, the optical sensor and the voltage application conditions. This will be described with reference to FIG. FIG. 12 is a logarithmic representation of the relationship between the exposure range when the image recording device (camera) is incident and the exposure range on the optical sensor. It is assumed that the exposure range that can be expressed using the liquid crystal recording medium and the optical sensor under a certain voltage application condition is ΔE1 (vertical axis) as shown in the figure. In logarithmic display, the incident light quantity and the light quantity on the photosensor have a linear relationship such as L1, and even if the diaphragm or lens system is changed, the inclination of this straight line does not change. Therefore, the exposure range that can be expressed is ΔE1. is there. In this way, when the incident light is divided into two lights of different ranges, such as L1 and L2, and they are applied to different parts of the photosensor, the exposure range that can be expressed is ΔE1.
However, for incident light, E0-E1 and E2-E
It is possible to record images in different exposure areas as shown in FIG. The exposure range can be expanded to ΔE2 by combining these two images. As can be seen from the figure, the expansion amount of the dynamic range is determined by the distribution ratio of the exposure amount, and when the ratio of L1 and L2 is 10: 1, the exposure range is expanded 10 times (optical density 1). Further, the amount of expansion may be set by the optical system so as to compensate the shortage of the exposure range of the medium, and is not particularly limited.

Next, composition of image information will be described with reference to the drawings. When images are recorded on different portions of the medium using the above-described method so as to have the characteristic curves of S1 and S2 as shown in FIG. 13, the characteristics S1 and S2 are changed to S1 ′ as shown in FIG. An image with an expanded exposure range can be obtained by converting as in S2 ′ and combining these. The image composition is not limited to linear conversion, but can be converted in any form suitable for the image characteristics.

In the above description, an example in which the image is divided into two areas and the recording conditions are changed has been described, but it goes without saying that the recording conditions may be changed into three or more areas.

[0018]

According to the present invention, a recording area is divided into a plurality of areas, a plurality of images having different tones are simultaneously recorded by making recording conditions different for each area, and after reading, a plurality of images having different tones are combined to obtain a dynamic image. It becomes possible to reproduce by expanding the range.

[0019]

[Fabrication of optical sensor]

 (Example 1) The following structure was used as a charge generating substance.

[0020]

[Chemical 1]

3 parts of fluorenone azo pigment having 1 part of polyester resin and dioxysan: cyclohexane =
It was mixed with 196 parts of a 1: 1 mixed solvent and sufficiently kneaded with a mixer to prepare a coating liquid. This solution was applied to the ITO side on a glass substrate having an ITO transparent electrode (film thickness: about 500Å, resistance: 80Ω / □) and dried at 100 ° C. for 1 hour to form a charge generation layer having a film thickness of 0.3 μm. Next, as the charge transport layer, the following structure

[0022]

[Chemical 2]

3 parts of para-dimethyl stilbene having and 1 part of polystyrene resin are mixed with dichloromethane: 1, 1, 2-
A coating solution was prepared by mixing and dissolving 170 parts of the mixed solvent in trichloroethane = 68: 102. This solution was applied onto the charge generation layer and dried at 80 ° C. for 2 hours to give a film thickness of 10 μm.
Was formed on the charge transport layer. This optical sensor is referred to as sensor A.

[Preparation of Liquid Crystal Recording Medium] (Example 2) 4 parts of dipentaerythritol hexaacrylate, smectic liquid crystal S6 (trade name; manufactured by Merck)
6 parts, fluorine-based activator Florard FC-430 (trade name; manufactured by 3M Co.) 0.2 parts, photopolymerization initiator "Darocur 1"
173 "(trade name; manufactured by Merck & Co.) 0.2 part of the mixture was adjusted to a solid content of 30% with xylene. This solution was applied to the ITO side surface of a glass substrate having an ITO transparent electrode (thickness: about 500Å, resistance: 80Ω / □) with a blade coater having a gap thickness of 50 μm and kept at 50 ° C.,
An information recording medium having an information recording layer with a film thickness of about 6 μm was produced by irradiating UV light of 0.3 mJ / cm ² . This information recording medium cross section was extracted with liquid crystal using hot methanol,
After drying, scanning electron microscope (Hitachi, Ltd.)
Manufactured by S-800, 10000 times), the surface of the layer was covered with an ultraviolet curable resin having a thickness of 0.6 μm, and the inside of the layer was filled with resin particles having a particle diameter of 0.1 μm. It was found to have a structure. This information recording medium is referred to as medium A.

[Measurement of Characteristics of Optical Sensor] (Example 3) FIG. 15 shows a method of measuring characteristics of an optical sensor. As shown in the figure, a gold electrode 14 is formed on the photoconductive layer 13 of the photosensor 10, a constant voltage is applied between the gold electrode and the transparent electrode 12 of the photosensor, and after a predetermined time, the light source 4
Light is emitted from No. 1 and transmitted light is detected by the photoelectric conversion element 61 as a timing signal. At this time, the current flowing between the gold electrode and the transparent electrode 12 of the optical sensor is monitored by the oscilloscope 70. An example of the measurement result is shown in FIG. The current immediately before the start of light irradiation is set as the dark current of this optical sensor, and after the light irradiation, 33
The difference between the current value after msec (1/30 msec) and the dark current is defined as the photocurrent. When dark current was measured for the optical sensor of Example 1, the dark current value when applying 300 V was 1.0.
It was × 10 ^-5 A / cm ² .

Example 4 [Measurement of Resistance Value of Liquid Crystal Recording Medium] I was formed on the liquid crystal recording layer of the liquid crystal recording medium prepared in Example 2 by a sputtering method.
A TO electrode is formed, a liquid crystal recording medium 20 and a capacitor C having an appropriate capacity are connected in series as shown in FIG. 17A, a voltage is applied between the transparent electrode and the liquid crystal layer, and the current value is measured. As shown in FIG. 17B, assuming that the liquid crystal recording medium is a parallel circuit of resistance and capacitance, a straight line is obtained by plotting the logarithm of the current value against the time, and the resistance value of the liquid crystal recording medium is obtained from the inclination. Desired. The volume resistivity thus obtained was 2.5 × 10 ¹¹ Ωcm.

(Example 5) [Fabrication of optical sensor having different electrical conductivity] A charge generation layer was formed in the same manner as in Example 1, and then 5 parts of paradimethylstilbene as a charge transport material and 1 part of polystyrene resin. And dichloromethane: 1,1,2-trichloroethane =
A coating liquid was prepared by mixing and dissolving 200 parts of 68: 102 mixed solvent. This solution is applied on the charge generation layer,
It was dried at 80 ° C. for 2 hours to form a charge transport layer having a film thickness of 10 μm. When the dark current value of this optical sensor was measured by the method described in Example 3, it was 1.2 × 10 ⁻⁵ A / cm ² when a voltage of 300 V was applied. This optical sensor is referred to as sensor B.

(Sixth Embodiment) [Recording of Information] The optical sensor of the first embodiment and the liquid crystal recording medium of the second embodiment are arranged facing each other with an air gap of 9 μm as shown in FIG. 33 msec
Simultaneously with the projection exposure, 700 V and 90 msec were applied between both electrodes so that the photosensor side became positive, and then the liquid crystal recording medium was observed. As a result, it was observed that the transmittance changed depending on the exposure amount.

(Example 7) [Reading of Image] After recording information by the method of Example 6, the optical sensor and the liquid crystal recording medium are separated from each other, and the liquid crystal recording medium is irradiated with ultraviolet rays in a structure as shown in FIG. Was converted into an electric signal by a CCD sensor. The light amount of the light source was adjusted and converted into an 8-bit digital signal so that the signal in the portion where the liquid crystal recording medium was perfectly oriented was 255. FIG. 18 shows the relationship between the exposure amount and the read value. The optical sensor of Example 5 and the liquid crystal recording medium of Example 2 were also subjected to gray scale exposure in the same manner as in Example 6 and applied with a voltage of 700 V for 90 msec to record an image. The given image was read in the same manner as above. Comparing the relationship between the exposure amount and the read value in the case where the sensor A and the sensor B are used, when the sensor B is used, the conductivity of the dark portion is high, and therefore, compared with the case where the sensor A is used, it is faster. Since the threshold value of the liquid crystal recording medium is obtained, when the image recording is performed under the same conditions (applied voltage, time) using both, the sensor B
The transmittance of the dark area becomes higher when is used. Further, when comparing the ranges of the exposure amounts to be image-recorded, the lower exposure region can be recorded by using the sensor B, but the exposure amount that saturates becomes smaller, so the exposure range that can be expressed is the sensor A and B. does not change. However, since the exposure areas recorded by the sensors A and B are different, it is possible to obtain an image with a wide exposure range by simultaneously recording using the sensors A and B and synthesizing the recorded images.

(Example 8) [When liquid crystal recording media having different resistance values are used] Example 2
Similarly, the solution prepared in 1. was applied on a substrate having an ITO transparent electrode and irradiated with 0.2 mJ / cm ² UV light to prepare an information recording medium having an information recording layer having a film thickness of 60 μm. When the volume resistance value of this medium was measured by the method of Example 4, it was 1.0 × 10 ¹¹ Ωcm. This medium is called medium B.

Image recording was performed in the same manner as in Example 6 by combining the optical sensor A with the medium A and medium B, and the recorded image was read in the same manner as in Example 7. As a result, when medium A was used, medium B was used. Since the threshold value of the liquid crystal recording medium is reached faster than the case of using, the dark area transmittance is higher when the medium A is used as in FIG. Since the areas are different, the exposure range could be expanded by combining the two.

(Embodiment 9) [Case of recording conditions] Even when the same optical sensor and liquid crystal recording medium are used, by changing the applied voltage and the applied time, an exposure area where recording can be performed as shown in FIG. Can be changed. Projection exposure was performed using the sensor A and the medium A in the same manner as in Example 6, and the applied voltage was 720 V and 90 m.
As a result of applying a voltage for sec and recording an image, when 720 V was applied, the threshold value of the liquid crystal recording medium was reached earlier than when 700 V was applied, and the same results as in FIG. 16 were obtained. Similar results were obtained when the voltage application time was changed.

(Example 10) [Using optical sensors having different sensitivities] [Method for producing sensor C] An ITO film having a thickness of 100 nm was formed by sputtering on a glass substrate having a thickness of 1.1 mm that had been thoroughly washed. Then, an electrode layer was obtained. The following structure as a charge generating agent on the electrode

[0034]

[Chemical 3]

40 parts by weight of the pyrrolopyrrole pigment having the above are mixed with 1 part by weight of polyvinyl butyral resin (BMS: Sekisui Chemical Co., Ltd.) and 120 parts by weight of 1,2-dichloroethane, and dispersed with a paint shaker for 3 hours. To obtain a coating solution, which was applied with a spinner at 3000 rpm for 0.4 seconds and then dried at 100 ° C. for 1 hour to laminate a charge generation layer having a film thickness of 300 nm. The following structure is used as a charge transfer agent on this charge generation layer.

[0036]

[Chemical 4]

3 parts by weight of the eminane derivative of, 2 parts by weight of polystyrene resin (HRM-3 manufactured by Denki Kagaku Kogyo KK),
A coating solution prepared by mixing 22 parts by weight of 1,1,2-trichloroethane and 14 parts by weight of dichloromethane was spun with a spinner to 40
After coating at 0 rpm for 0.4 seconds, it was dried at 80 ° C. for 2 minutes, and a charge transport layer was laminated to obtain a photosensor having a photoconductive layer having a film thickness of 20 μm and comprising a charge generation layer and a charge transport layer. .
This optical sensor is referred to as sensor C.

[Method of Manufacturing Sensor D] An ITO film having a film thickness of 100 nm was formed by sputtering on a glass substrate having a thickness of 1.1 mm that had been thoroughly washed to obtain an electrode layer. The following structure as a charge generating agent on the electrode

[0039]

[Chemical 5]

3 parts by weight of a bisazo pigment having 1 part by weight, 1 part by weight of polyvinyl butyral, 98 parts by weight of 1,4-dioxane, and 98 parts by weight of cyclohexanone are mixed and dispersed for 6 hours in a paint shaker to prepare a coating solution, which is then mixed with a spinner.
After coating at 400 rpm for 0.4 seconds, it was dried at 100 ° C. for 1 hour, and a charge generation layer having a film thickness of 300 nm was laminated.

On the charge generation layer, the following structure is used as a charge transfer agent.

[0042]

[Chemical 6]

A coating solution prepared by mixing 3 parts by weight of the compound of 3 parts, 2 parts by weight of polystyrene, 22 parts by weight of 1,1,2-trichloroethane, and 14 parts by weight of dichloromethane was applied with a spinner at 400 rpm for 0.4 seconds, After drying at 80 ° C. for 2 hours, a charge transport layer was laminated to obtain a photosensor having a photoconductive layer having a film thickness of 20 μm and composed of a charge generation layer and a charge transport layer. This optical sensor is referred to as sensor D.

FIG. 19 shows the results of measuring the photocurrent values of the sensors C and D by the method of the third embodiment. The figure shows the relationship between the photocurrent value and the exposure intensity 33 msec after the start of exposure. Since the dark current values of these optical sensors are almost the same, the exposure range that can be recorded does not change when image recording is performed using these optical sensors, but since the exposure area is different, image recording is performed simultaneously using each optical sensor. Then, by combining the two, an image with a wide exposure range could be obtained.

(Embodiment 11) [In the case of using an optical system] As shown in FIG. 20, the light is divided by the optical system so that the intensity becomes 10: 1, and the different portions of the optical sensor are exposed to light. Image recording was performed in the same manner as in No. 6, two images having different exposure areas were obtained, and the results shown in FIG. 21 were obtained. These two images were read and then combined to obtain an image with a wide exposure range.

[0046]

As described above, according to the present invention, a recording area is divided into a plurality of areas, a plurality of images having different tones are simultaneously recorded by changing recording conditions for each area, and a plurality of images having different tones are read after reading. By synthesizing the images, the dynamic range can be expanded.

[Brief description of drawings]

FIG. 1 is a diagram illustrating image recording using a polymer-dispersed liquid crystal medium.

FIG. 2 is a diagram showing a reading device.

FIG. 3 is a diagram showing a time change of a voltage applied to a liquid crystal recording medium.

FIG. 4 is a diagram showing a relationship between an exposure amount and a modulation degree when recording is performed while changing a voltage application time.

FIG. 5 is a diagram showing an example in which image exposure is performed simultaneously using two types of optical sensors having different conductivity.

FIG. 6 is a diagram showing an example of simultaneously performing image exposure using liquid crystal recording media having different characteristics.

FIG. 7 is a diagram showing a voltage change applied to a liquid crystal recording medium when two types of photosensors having different conductivity are simultaneously used for image exposure.

FIG. 8 is a diagram showing a calculation result of a voltage applied to a liquid crystal medium when an applied voltage is changed.

FIG. 9 is an explanatory diagram in the case of changing the voltage application time applied to the liquid crystal recording medium.

FIG. 10 is an explanatory diagram when changing the threshold value of the liquid crystal recording medium.

FIG. 11 is an explanatory diagram in the case where different voltages or voltage application times are applied to two partial electrodes obtained by patterning the electrodes.

FIG. 12 is a logarithmic representation of the relationship between the exposure range upon incidence on the image recording apparatus and the exposure range on the optical sensor.

FIG. 13 is a diagram showing recorded image recording data having different characteristics.

FIG. 14 is a diagram illustrating image composition.

FIG. 15 is a diagram illustrating a method for measuring characteristics of an optical sensor.

FIG. 16 is a diagram showing a measurement result of characteristic measurement of an optical sensor.

FIG. 17 is a diagram illustrating calculation of volume resistivity of a liquid crystal recording medium.

FIG. 18 is a diagram showing a relationship between an exposure amount and a read value.

FIG. 19 is a diagram showing a photocurrent measurement result when sensors having different characteristics are used.

FIG. 20 is a diagram showing an example of a case where image exposure is performed with different exposure intensities.

FIG. 21 is a diagram showing measurement results when the exposure intensity is changed.

[Explanation of symbols]

10 ... Optical sensor, 20 ... Liquid crystal recording medium, 30 ... Power supply, 4
0 ... Light source, 60 ... Photoelectric converter.

Claims (11)

[Claims] 1. An optical sensor having a photoconductive layer formed on an electrode and an information recording medium having a polymer-dispersed liquid crystal layer in which a liquid crystal is dispersed and fixed in a resin formed on an electrode are arranged to face each other with a gap therebetween. In a method of recording an image by applying a voltage at the same time as image exposure through an exposure optical system, the recording area is divided into a plurality of areas, and the recording conditions are different for each area to record a plurality of images with different tones at the same time. An information recording / reproducing method having a dynamic range expanding function, which is characterized by synthesizing a plurality of images having different tones after reading. 2. The information recording / reproducing method having a dynamic range expanding function according to claim 1, wherein recording conditions are made different by using optical sensors having different voltage-current characteristics for each area. 3. An information recording / reproducing method having a dynamic range expanding function according to claim 1, wherein recording conditions are made different by using liquid crystal recording media having different characteristics for each area. 4. The information recording / reproducing method having a dynamic range expanding function according to claim 1, wherein recording conditions are made different by using different voltage application time and applied voltage for each area. 5. The information recording / reproducing method having a dynamic range expanding function according to claim 1, wherein recording conditions are made different by using photosensors having different photocurrent characteristics for each area. 6. The information recording / reproducing method having a dynamic range expanding function according to claim 1, wherein image exposure is performed with a different light amount for each area to change recording conditions. 7. A plurality of types of optical sensors having a photoconductive layer formed on an electrode and having different voltage-current characteristics, and an information recording medium having a polymer dispersed liquid crystal layer in which liquid crystal is dispersed and fixed in a resin formed on the electrode. A device for performing image recording by applying a voltage at the same time as image exposure by arranging the two in opposition to each other through a gap, and means for reading images of different tones recorded by imagewise exposing the plurality of types of optical sensors at the same time. An information recording / reproducing apparatus having a dynamic range expansion function, comprising a combining processing unit for combining a plurality of images after reading. 8. An optical sensor having a photoconductive layer formed on an electrode and an information recording medium having a plurality of types of polymer dispersed liquid crystal layers having different characteristics in which liquid crystal is dispersed and fixed in a resin and having different characteristics are formed on an electrode. A device for recording an image by opposingly arranging the liquid crystal layer through image exposure by applying a voltage at the same time as image exposure, and means for reading images of different tones recorded by simultaneously performing image exposure on the liquid crystal layers of a plurality of types through an optical sensor. And an information recording / reproducing apparatus having a dynamic range expansion function, which comprises a combining processing unit for combining a plurality of images after reading. 9. An optical sensor having a photoconductive layer formed on an electrode and an information recording medium having a polymer-dispersed liquid crystal layer in which a liquid crystal is dispersed and fixed in a resin formed on an electrode are arranged to face each other with a gap therebetween. In an apparatus for recording an image by applying a voltage at the same time as image exposure, an optical system for dividing the image exposure into a plurality of parts to expose different parts of the photosensor, and applying different voltage application time and applied voltage to each part Voltage applying means,
An information recording / reproducing apparatus having a dynamic range expanding function, comprising: a unit for reading images of different tones recorded under different conditions by a voltage applying unit; and a combining processing unit for combining a plurality of images after reading. 10. A plurality of kinds of photosensors having a photoconductive layer formed on an electrode and having different photocurrent characteristics, and an information recording medium having a polymer dispersed liquid crystal layer in which liquid crystal is dispersed and fixed in a resin formed on the electrode. A device for performing image recording by applying a voltage at the same time as image exposure by arranging the two in opposition to each other through a gap, and means for reading images of different tones recorded by imagewise exposing the plurality of types of optical sensors at the same time. An information recording / reproducing apparatus having a dynamic range expansion function, comprising a combining processing unit for combining a plurality of images after reading. 11. An optical sensor having a photoconductive layer formed on an electrode and an information recording medium having a polymer-dispersed liquid crystal layer in which a liquid crystal is dispersed and fixed in a resin formed on an electrode are arranged to face each other with a space therebetween. In an apparatus for performing image recording by applying a voltage at the same time as image exposure, an optical system for dividing the image exposure into a plurality of parts to expose images of different light amounts to different portions of the photosensor, and a different light amount by the optical system. An information recording / reproducing apparatus having a dynamic range expansion function, comprising: a unit for reading recorded images of different tones and a combining processing unit for combining a plurality of images after reading.